vulnerability
Debian: CVE-2022-49501: linux -- security update
Severity | CVSS | Published | Added | Modified |
---|---|---|---|---|
7 | (AV:L/AC:L/Au:N/C:C/I:C/A:C) | 2025-02-27 | 2025-02-27 | 2025-03-10 |
Description
In the Linux kernel, the following vulnerability has been resolved:
usbnet: Run unregister_netdev() before unbind() again
Commit 2c9d6c2b871d ("usbnet: run unbind() before unregister_netdev()")
sought to fix a use-after-free on disconnect of USB Ethernet adapters.
It turns out that a different fix is necessary to address the issue:
https://lore.kernel.org/netdev/18b3541e5372bc9b9fc733d422f4e698c089077c.1650177997.git.lukas@wunner.de/
So the commit was not necessary.
The commit made binding and unbinding of USB Ethernet asymmetrical:
Before, usbnet_probe() first invoked the ->bind() callback and then
register_netdev(). usbnet_disconnect() mirrored that by first invoking
unregister_netdev() and then ->unbind().
Since the commit, the order in usbnet_disconnect() is reversed and no
longer mirrors usbnet_probe().
One consequence is that a PHY disconnected (and stopped) in ->unbind()
is afterwards stopped once more by unregister_netdev() as it closes the
netdev before unregistering. That necessitates a contortion in ->stop()
because the PHY may only be stopped if it hasn't already been
disconnected.
Reverting the commit allows making the call to phy_stop() unconditional
in ->stop().
Solution

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